Recommendations on the protein requirements of elderly human subjects are based largely on data from healthy young adults. The objective of the proposed research work is to directly estimate the protein requirement of elderly men and women and to evaluate the adequacy of the current recommendations for protein intake in this age-group. Nitrogen balance studies are being conducted to determine (a) obligatory N losses and (b) the relationship between these latter losses and the minimum amount of high quality protein required to achieve satisfactory N balance in this age group. Both short-term and long-term N balance studies are being conducted. The effects of chronic morbidity on protein needs of older people are to be explored as these studies continue.